1. Field of the Invention
The present invention relates to a method of processing an image in an electronic video endoscopy system which is adapted to pick up an image using a surface sequential technique.
2. Description of the Related Art
Conventionally, there is known an RGB surface sequential technique in which color images corresponding to respective color illumination lights can be obtained sequentially from a single, two-dimension CCD sensor. This technique is effective in a case where two or more two-dimensional CCD sensors cannot be installed and, recently, it has been applied to an electronic video endoscopy system for medical use.
The above-mentioned electronic video endoscopy system is arranged such that it is able to simultaneously convert color image information which has been picked up sequentially and which corresponds correspondingly to illumination lights of red (R), green (G) and blue (B) field memories and which is also able to reproduce the color image information as color images in a color TV.
However, in the electronic video endoscopy system that picks up images using a surface sequential technique, for prevention of line flickers, the field data corresponding to the respective R, G and B color image information must be taken from the same kind of fields. For this reason, according to the prior art, the field data corresponding to either odd or even fields only is read out from a CCD sensor, or both of the odd and even field data are added together and the resultant data is read out at once from the CCD sensor.
Accordingly, the resolution of the CCD in the vertical direction is half of the resolution that the CCD inherently has.
Also, an ordinary electronic video endoscopy system employs a 1/2-inch or 1/3-inch size optical, full-frame CCD (including 500 (H).times.400 (V)=200,000 pixels) for an ordinary TV. However, with the development of an endoscope having a smaller diameter, the CCD that can be applied to such smaller diameter endoscope provides a local observation CCD which has an optical size of the order of 1mm2.
Therefore, if the CCD is operated in a currently-used system, then screen size is determined by the area ratio thereof. That is, when the CCD having an optical size of 1mm2 is used, the screen size thereof becomes too small to be practically effective.